TD may be busy, in the meantime I can only tell you that it works for me.
The icons file in the pilot folder works offline only. I have shown my settings below, but I also tried yours and they work the same, overriding the default settings. My RCU is the same as yours.
Code:
mp_dotrange FRIENDLY DOT 20.0 COLOR 0.01 RANGE 0.01 TYPE 0.01 ID 0.2 NAME 0.1 ALTICON 6.0 ALTSYMBOL o ALTCOLOR 2
mp_dotrange FOE DOT 20.0 COLOR 0.01 RANGE 0.01 TYPE 0.01 ID 0.2 NAME 0.1 ALTICON 6.0 ALTSYMBOL x ALTCOLOR 1
There may be another file in your main folder called icon.rcu. It is only active if the main rcu has the added line
It has the same format and changes the icon settings for all players if you run a dogfight server. If the settings are different, it will override and rewrite the pilot icons file to match, even if you are playing offline.